Many times, the content in a biological conduit needs to be sampled and analyzed. Take human or animal intestinal tract or gut as an example. Small intestine (AKA small bowel) is the part of the gastrointestinal tract between the stomach and the large intestine. The average length of the small intestine in a living person is about 6 meters. The small intestine does not only digest food and absorb nutrients and minerals, but also support the body's immune system. Jejunum is the midsection of the small intestine, connecting the duodenum to the ileum. It is about 2.5 m long, and contains the plicae circulares, and villi that increase its surface area. In the jejunum, digestion products such as sugars, amino acids, and fatty acids are absorbed into the bloodstream. The ileum is the final section of the small intestine, and is about 3 m long. The ileum absorbs mainly vitamin B12 and bile acids, as well as any other remaining nutrients. The ileum joins to the cecum of the large intestine at the ileocecal junction. Peyer's patches located within the ileum are an important part of the digestive tract's local immune system. These patches are part of the lymphatic system, and provide a site for antigens from potentially harmful bacteria or other microorganisms in the digestive tract to be sampled, and subsequently presented to the immune system. The jejunum and ileum are suspended in the abdominal cavity by mesentery. The mesentery is part of the peritoneum. Arteries, veins, lymph vessels and nerves travel within the mesentery.
Large intestine (AKA large bowel) includes many sections along its 1.5-meter length, such as cecum and appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal. Lymphatic drainage from the ascending colon and proximal two-thirds of the transverse colon is to the colic lymph nodes and the superior mesenteric lymph nodes, which drain into the cisterna chyli. The lymph from the distal one-third of the transverse colon, the descending colon, the sigmoid colon, and the upper rectum drain into the inferior mesenteric and colic lymph nodes. The lower rectum to the anal canal above the pectinate line drain to the internal iliac nodes. The anal canal below the pectinate line drains into the superficial inguinal nodes.
Moreover, the immunological function of the intestinal tract is also associated with the complex community of microorganisms called gut flora or gut microbiota. For example, the large intestine houses over 700 species of bacteria that perform a variety of functions, as well as fungi, protozoa, and archaea. The amount of microbes in a human distal gut is in the vicinity of 100 trillion. In humans, the gut flora is established at one to two years after birth, and by that time, the intestinal epithelium and the intestinal mucosal barrier that it secretes have co-developed in a way that is tolerant to, and even supportive of, the gut flora and that also provides a barrier to pathogenic organisms. Some human gut microorganisms benefit the host by fermenting dietary fiber into short-chain fatty acids (SCFAs), such as acetic acid and butyric acid. Intestinal bacteria also play a role in synthesizing vitamin B and vitamin K as well as metabolizing bile acids, sterols, and xenobiotics. The systemic importance of the SCFAs and other compounds they produce are like hormones, and the gut flora itself appears to function like an endocrine organ. Dysregulation of the gut flora has been correlated with a host of inflammatory and autoimmune conditions.
People tend to underestimate the importance of gut flora, which plays many key roles. The gut flora community defends against pathogens by fully colonizing the space, making use of all available nutrients, and by secreting compounds that kill or inhibit unwelcome organisms that would compete for nutrients with it. It develops and maintains the intestinal epithelium and inducing antibody production. It helps to metabolize otherwise indigestible compounds in food. The gut flora may even train and develop the immune system.
Surprisingly, recent study shows that biochemical signaling can take place between the gastrointestinal tract and the central nervous system, via the so-called “gut-brain axis”. The gut-brain axis includes the central nervous system, neuroendocrine and neuroimmune systems including the hypothalamic-pituitary-adrenal axis (HFA axis), sympathetic and parasympathetic arms of the autonomic nervous system including the enteric nervous system and the vagus nerve, and the gut microbiota. As a bidirectional neurohumoral communication system, the gut-brain axis is important for maintaining homeostasis and is regulated through the central and enteric nervous systems and the neural, endocrine, immune, and metabolic pathways. The gut flora can produce a range of neuroactive molecules, such as acetylcholine, catecholamines, γ-aminobutyric acid, histamine, melatonin, and serotonin, which is essential for regulating peristalsis and sensation in the gut. Changes in the composition of the gut flora due to diet, drugs, or disease correlate with changes in levels of circulating cytokines, some of which can affect brain function. Likewise, chronic or acutely stressful situations activate the hypothalamic-pituitary-adrenal axis, causing changes in the gut flora and intestinal epithelium, and possibly having systemic effects. Additionally, the cholinergic anti-inflammatory pathway, signaling through the vagus nerve, affects the gut epithelium and flora. Hunger and satiety are also integrated in the brain. There may be a relationship between the gut flora and anxiety disorders and mood disorders including depression; schizophrenia, autism, Parkinson's disease, and obsessive-compulsive disorder.
That being said, it is critically important to sample and study the content in an intestinal tract. However, the human gut is largely unexplored, except for post mortem autopsies, which do not reflect much of the most important living dynamic phenomena and conditions. Many diseases with origin in human gut are of unknown causes, so only symptoms are treated. For example, the remote and inaccessible 15′ sections of intestines, beyond the 6 feet up and 6 feet down as viewed by endoscopy/colonoscopy instruments, remain unexplored in live humans. Even these upper and lower extremities that are viewed by camera can only be treated for visible damage, such as polyps or ulcers. A camera pill may be swallowed, and pictures are taken throughout the intestinal tract, but the information gleaned is largely qualitative. As such, quantitative in-vivo data and measurements are generally not available.
There is hence a serious need to analyze the biochemical, biological, physiological, and bioengineering processes taking place within the entire human intestinal tract, as precisely as in other anatomical systems (e.g. DNA, and microbiology). Advantageously, the present invention provides a sampling device capable of continuously sampling the content in human or animal intestinal tract, and a method thereof. The present invention enables an easy and convenient operation for collection and preservation of intestinal bio/chemical profile for external analysis, and measurements of many in vivo conditions. The invention can support medical professionals' decisions-making such as construction of mathematical, physiological, biochemical, and other engineering models; delineation of causes of diseases originating within the gut; and prescribing diets or medications.